A radioactive mineral from Mozambique related to davidite

Abstract

Early in 1947 a black, opaque, radioactive mineral resembling samarskite in appearance was discovered at Mavnzi in the Tete distrier of Mozambique, Portuguese East Africa. Two small specimens, one a rough twinned crystal with trigonal symmetry (fig. 3), were sent by h. M. Macgregor; then Director of the Geological Survey of Southern Rhodesia, to the British Museum (Natural History) for investigation, and a chemical analysis by E. Golding (table I, no. 2) followed later in the same year. X-ray photographs of fragments and powder from both specimens were taken, but revealed on development no diffraction spots, lines, or haloes. Only after prolonged heat-treatment could powder lines characteristic of crystalline material be obtained. The metamict nature of the mineral before heat-treatment is not unexpected in view of its chemical composition, optical isotropy, and glassy fracture.